1. Field of the Invention
The present invention broadly relates to a new and improved construction of a controlled deflection roll, also referred to in the art as a roll with bending or sag compensation.
In its more particular aspects the present invention relates to an improved construction of a controlled deflection roll comprising a roll shell rotatable about a stationary or non-rotatable support, the rotatable roll shell being supported or braced at the stationary support by means of at least one support device exerting a pressing force in a pressing plane. Approximately at the region of the ends of the roll shell there are provided devices for exerting a rotational moment and having an axis extending substantially perpendicular to the pressing plane.
2. Discussion of the Background and Material Information
Controlled deflection rolls are well known to the art, for example, from U.S. Pat. No. 3,802,044 and the cognate Federal Republic of Germany Patent No. 2,230,139, published Jan. 25, 1973 as well as U.S. Pat. No. 3,885,283 and the cognate Federal Republic of Germany Patent No. 2,230,139, published May 9, 1974. In these prior constructions of controlled deflection rolls a row of hydrostatic support elements braces or supports the rotatable roll shell or jacket against the non-rotatable or stationary support or beam. However, it is also known in this technology to support the rotatable roll shell throughout its entire length in relation to the stationary support or beam by one or a number of different types of support devices, such as hydrodynamic, magnetic or other support elements or even by means of one or a number of pressure chambers. Moreover, the controlled deflection rolls may be of the type where the opposite ends of the roll shell are mounted, for example, by means of pendulum bearings at the stationary support, or, however, there may be provided controlled deflection rolls of the type where also the opposite ends of the roll shell are freely movable at least in the pressing direction or are guided by a guide device.
With such controlled deflection rolls it has been found to be advantageous to provide, in addition to the pressing action of the support elements, devices at the opposite ends of the roll shell which intentionally exert at the opposite ends of the roll shell a force or rotational moment or torque having an axis disposed perpendicular to the pressing plane. However, the application of such rotational moment at the roll shell through the opposite ends of the roll shell is associated with disturbing disadvantages in such state-of-the-art controlled deflection rolls.
From the Federal Republic of Germany Patent No. 2,325,721 and the cognate Swiss Patent No. 568,105, published Oct. 10, 1975, it is known, for instance, to provide at the opposite ends of the roll shell, in addition to the radially effective support elements, axially offset, but likewise radially acting support elements which, however, are effective in the opposite direction. With simultaneous operation of the counter support elements and the neighboring support elements there is here thus produced at the opposite ends of the roll shell the desired rotational moment or torque. What is disadvantageous with this prior art construction of controlled deflection roll is that, by virtue of the pressing forces exerted upon the roll shell by the counter support elements and the support elements, the roll shell is deformed in a difficult to control manner, and moreover, at the different points of action of the counter support elements and the support elements the roll shell is caused to assume an undefined oval shape. Additionally, the magnitude of the thus produced force or rotational moment is limited.
In U.S. Pat. No. 4,757,585 or the European Patent Application No. 0,241,442, published Oct. 14, 1987, there are also disclosed controlled deflection rolls where the support elements effective radially at the opposite ends of the roll shell in opposite directions do not act directly upon the opposite ends of the roll shell, rather upon the cylindrical inner surface of a respective sleeve inserted into the opposite ends of the roll shell, or else axially upon a shoulder at the opposite ends of the roll shell and which carries the bearings at the stationary support externally of the roll shell. Here, what is deemed to be a shortcoming is the complicated construction of the controlled deflection roll or crown roll as well as the space requirements needed for the sleeves, resulting in weakening of the stationary support at the opposite ends of the roll shell.